The present invention relates to a control device for a vehicle which is an electric vehicle or a plug-in hybrid vehicle. More specifically, the present invention relates to a control device for a vehicle including a traction motor, a high-voltage battery for supplying electric power to the motor, and a battery charger for charging the high-voltage battery by using an external power supply.
An electric vehicle or a plug-in hybrid vehicle has been known which is configured such that power obtained from a domestic power supply is charged into a high-voltage battery and which is capable of traveling by using only the power in the high-voltage battery.
Such a vehicle includes a control device (also referred to as an “integrated ECU”) configured to manage information on components including a motor, an engine, a battery, and the like, and to perform integrated control thereof. Alternatively, in such a vehicle, the aforementioned function is often imparted to a control device for any of these components.
In addition, as disclosed in JP 2-290106 A, such a vehicle is generally configured such that the drive control and the control of charging using an external power supply are performed separately from each other to prevent malfunction.
Furthermore, the vehicle being the electric vehicle or the plug-in hybrid vehicle involves external charging which is not carried out by conventional gasoline-powered vehicles. Accordingly, there are various conceivable patterns of vehicle conditions at the time of a failure, for example:
(1) Whether the failure occurs in the course of carrying out a driving cycle or an external charging cycle;
(2) Whether the failure occurs before the start of any of these cycles;
(3) Whether the cycle previously carried out was the driving cycle;
(4) Or the cycle previously carried out was the external charging cycle.
Hence it may be impossible to carry out the optimum fail safe process without considering these factors.
Now, a case of occurrence of a failure that requires limp-home mode driving will be considered as an example. Such a failure may be a failure of a DC/DC converter or a high-voltage battery-related component which may incur significant degradation in mileage, or a failure of a drive system or a brake-related component which may cause significant power output limitation, for instance.
If the failure is detected in the course of the driving cycle, it is disadvantageous for a driver to stop the vehicle immediately at that place. Therefore, it is obvious that the limp-home mode driving should be permitted in this case.
Meanwhile, if the permission in the event of the failure in the course of the driving cycle as described above is similarly applied to a case in which the failure is detected before the start of the driving cycle, then the vehicle will fall into the limp-home mode driving immediately after the start of the drive. Therefore, the vehicle may be stopped before reaching a place where the vehicle has no possibility of a collision with another vehicle, and does not obstruct the traffic. In this case, it is not always appropriate to permit the driving of the vehicle.
On the other hand, there may also be a case in which the driver has noticed an anomaly already and he or she may be stopping the vehicle temporarily and attempting to restart. For this reason, it is not always appropriate to prohibit the driving of the vehicle when the failure was detected before the start of the driving cycle.
One of objects of the limp-home mode driving is to move the vehicle to a place where the vehicle has no possibility of a collision with another vehicle, and does not obstruct traffic. In the above-mentioned cases, the appropriateness to permit the start of driving of the vehicle should be determined based on whether or not the vehicle is located at a place at the detection of the failure where the vehicle has no possibility of a collision with another vehicle, and does not obstruct the traffic, and whether or not the vehicle is in a condition in which the vehicle has no possibility of collision with another vehicle, and does not obstruct the traffic.
To attain this object, a diagnosis of a failure and the fail safe process must be executed not only based on the information on the driving cycle or the charging cycle being carried out at the moment, but also in consideration of the information on the driving cycle or the external charging cycle executed in the previous session.
To solve this problem, JP 8-294202 A proposes a method applicable to an electric vehicle including a driving controller and a charging controller, the method being configured to transmit failure detection information detected by one of the controllers to the other controller. Meanwhile, JP 2009-71901 A proposes a method of diagnosing a short-circuit failure of a charging conductor while a vehicle is being driven, and stopping a system after the stop of the vehicle, for example.
However, the above-described references, JP 8-294202 A and JP 2009-71901 A, have the following problems.
First, an object of the above-described JP 8-294202 A and the like is to expand a failure detection range of a main control circuit by exchanging the failure diagnosis information between the driving controller and the charging controller. Therefore, the technique according to JP 8-294202 A has a disadvantage that this technique is not intended for a system including a control device which is the integrated ECU configured to carry out the driving control and the charging control with the same controller.
Moreover, the above-described JP 8-294202 A and the like do not particularly consider the fail safe process after the detection of the failure, and therefore cannot solve the aforementioned problem.
An object of the above-described JP 2009-71901 A is also to expand a failure detection range by executing a failure diagnosis of components necessary for external charging while the vehicle is running, and thereby to further improve safety in that driving cycle. Therefore, the technique according to JP 2009-71901 A has a disadvantage that this technique cannot solve the aforementioned problem.